Fermenting Fungi Faster to Quell Whiteflies

A fungus with a penchant for attacking and killing silverleaf whiteflies and other crop pests could be the bioinsecticide to watch as scientists on both sides of the U.S.-Mexico border work to make it commercially viable.

Scientists with USDA’s Agricultural Research Service collaborated with Mycotech Corp. of Butte, Mont., to improve methods for economically producing large numbers of spores of the fungus Paecilomycesfumosoroseus (pay-SILL-o-my-sees fume-o-so-ROSE-ee-us). These spores can be spread in fields as a non-chemical, environmentally friendly weapon against the crop pests.

The ARS scientists modified earlier deep-tank fermentation technology that launched an arsenal of antibiotics against human disease. Since applying for a patent less than two years ago, the researchers have doubled the number of spores produced per tank and cut fermentation time from three days to less than two.

To be commercially viable, large and predictable numbers of spores produced months in advance of use may have to survive freeze-drying and long-term storage. Then they must spring vigorously from this Rip Van Winkle state when mixed with water and sprayed on insect pests.

In the latest benchmark achievement, 80 percent of spores that survived freeze-drying were still viable after 5 months of storage. One crucial difference: The scientists mixed the microbes with sustaining cornstarch, flour and sucrose before drying them.

Scientists at the Universidad Autonoma de Nuevo Leon, Monterrey, Mexico, have begun working with the ARS researchers to develop fermentation media that are more economical than the precisely defined recipes used earlier.

The scientists in Mexico are also working with ARS scientists in Weslaco, Texas, to make sure the spores do their job well in the greenhouse and in the field.

To further improve the spore survival rate, the international scientific team is conducting research to precisely define requirements for storage environments. Such requirements may involve packaging and temperature and humidity controls.

Scientific contact: Mark A. Jackson, USDA-ARS National Center for Agricultural Utilization Research, Peoria, Ill., phone (309) 681-6283, fax (309) 681-6686, e-mail jacksoma@ncaur1.ncaur.gov (beginning April 28: jacksoma@mail.ncaur.usda.gov).